While many methods have been used to separate fluid mixtures, e.g. of gas or vapor, by mass difference between components, it has been found that a particularly economical and effective method can make use of the tendency of the components to stratify in zones as the gas mixture is directed at high velocity along a curved flow path.
It is thus known to provide nozzles or jets which direct the fluid mixture along a curved surface and peel-off or skimming baffles or edges which divert a selected portion of the flow from this curved surface to respective channels, thereby separating the mixture into a relatively heavy component or fraction on one side of the skimming edge and a relatively light fraction or component on the opposite side of the skimming edge.
This technique can be used effectively to enrich a gas stream in U.sup.235, for example, or in general for uranium isotope separation by converting a mixtue of uranium isotopes into compounds of a corresponding gaseous or vapor state, e.g. the uranium hexafluoride, and subjecting the resulting mixture of the hexafluorides of the several uranium isotopes to a peel-off or skimming action, for example enriching the U.sup.235 hexafluoride content in the light fraction.
It has been proposed heretofore to provide relatively compact apparatus for this purpose utilizing a passage-forming structure into which the gas mixture is fed and which defines passages for the heavy fraction as well, the passages for the mixture opening through nozzle slots into flow-directing grooves or channels in which the stream is intercepted by the peel-off or skimming baffles or edges, thereby deflecting the heavy fraction to the appropriate passages while allowing the light fraction to escape between the nozzle edges and the skimming edges. The passages for the mixture to be separated and for the heavy component which has been separated from the mixture can alternate in the unit.
Such systems, as described in German Pat. No. 24 19 192, column 2, lines 32 to 41, are dependent for their efficiency on the maintenance of strict dimensional and positional tolerances for the components making up the unit.
In German Pat. No. 11 98 328, FIGS. 3 and 4, a complex device for the purposes described is disclosed with various cover plates and elements which must be assembled in a complex manner to form the unit, the assembly operations and the fabrication of the individual components affording opportunities for error and tolerance deviations which are additive or multiplicative.
It is also possible, utilizing these principles, to separate the gas or vapor mixture into three components, namely, a light fraction, a medium fraction and a heavy fraction, as described, for example in the Rosenbaum dissertation Entmischung der Uranisotope in einem Trenndusensystem mit zweifacher Strahlumlenkung and trifraktionarer Gasabsaugung, Karlsruhe University, Karlsruhe, Germany. In this system two successive nozzle grooves are provided to direct the gas stream along oppositely directed curved paths.
The trifractional separation resulting from this system has advantages in many cases. However, a trifractional separation utilizing the aforedescribed devices cannot be effected without unduly multiplying the number of components and parts of conventional apparatus thereby significantly increasing the assembly and tolerances problems.